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Mercury Windsor (1968–1993) specs: 302 ci (5.0L) 8-cylinder, 4.00 x 3.00 in (101.6 x 76.2 mm) bore and stroke. Rated 130-290 hp, 1968–1993.
The Mercury Windsor (1968–1993) is oversquare — the 4" bore exceeds the 3" stroke by 33.3% — a layout that favors airflow and RPM over leverage at the crank. The 3" stroke does not reach 4,000 ft/min of mean piston speed until about 8,000 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 37.8 ci (619 cc).
It is one of 24 engines in the Windsor family, sitting between the 221 ci and 351 ci members. 16 factory variants share these dimensions, rated from 130 to 290 hp across 1968–1993.
| Displacement | 302 ci / 5 L |
|---|---|
| Bore | 4" |
| Stroke | 3" |
| Cylinders | 8 |
| Configuration | V8 |
| Bore/stroke ratio | 1.333 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 130–290 hp |
| Years | 1968–1993 |
| Bore/stroke character | 1.333 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,000 ft/min — conservative for a street engine |
| Displacement per cylinder | 37.8 ci |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1968 | 210 hp | — |
| 1969 | 290 hp | — |
| 1970 | 290 hp | — |
| 1977 | 130 hp | — |
| 1978 | 134 hp | — |
| 1979 | 133 hp | — |
| 1980 | 130 hp | — |
| 1981 | 130 hp | — |
| 1984 | 140 hp | — |
| 1985 | 140 hp | — |
| 1986 | 150 hp | — |
| 1987 | 150 hp | — |
| 1988 | 155 hp | — |
| 1991 | 200 hp | — |
| 1992 | 200 hp | — |
| 1993 | 200 hp | — |